The micronucleus frequency in cytokinesis-blocked lymphocytes of cattle in the vicinity of a nuclear power plant

The lymph node stromal laminin α5 shapes alloimmunity

Lymph node stromal cells (LNSCs) regulate immunity through constructing lymphocyte niches. LNSC-produced laminin α5 (Lama5) regulates CD4+ T cells but the underlying mechanisms of its functions are poorly understood. Here we show that depleting Lama5 in LNSCs resulted in decreased Lama5 protein in the LN cortical ridge (CR) and around high endothelial venules (HEVs). Lama5 depletion affected LN structure with increased HEVs, upregulated chemokines, and cell adhesion molecules, and led to greater numbers of Tregs in the T cell zone. Mouse and human T cell transendothelial migration and T cell entry into LNs were suppressed by Lama5 through the receptors α6 integrin and α-dystroglycan. During immune responses and allograft transplantation, depleting Lama5 promoted antigen-specific CD4+ T cell entry into the CR through HEVs, suppressed T cell activation, and altered T cell differentiation to suppressive regulatory phenotypes. Enhanced allograft acceptance resulted from depleting Lama5 or blockade of T cell Lama5 receptors. Lama5 and Lama4/Lama5 ratios in allografts were associated with the rejection severity. Overall, our results demonstrated that stromal Lama5 regulated immune responses through altering LN structures and T cell behaviors. This study delineated a stromal Lama5-T cell receptor axis that can be targeted for immune tolerance modulation.

Role of lymph node stroma and microenvironment in T cell tolerance

Lymph nodes (LNs) are at the cross roads of immunity and tolerance. These tissues are compartmentalized into specialized niche areas by lymph node stromal cells (LN SCs). LN SCs shape the LN microenvironment and guide immunological cells into different zones through establishment of a CCL19 and CCL21 gradient. Following local immunological cues, LN SCs modulate activity to support immune cell priming, activation, and fate. This review will present our current understanding of LN SC subsets roles in regulating T cell tolerance. Three major types of LN SC subsets, namely fibroblastic reticular cells, lymphatic endothelial cells, and blood endothelial cells, are discussed. These subsets serve as scaffolds to support and regulate T cell homeostasis. They contribute to tolerance by presenting peripheral tissue antigens to both CD4 and CD8 T cells. The role of LN SCs in regulating T cell migration and tolerance induction is discussed. Looking forward, recent advances in bioengineered materials and approaches to leverage LN SCs to induce T cell tolerance are highlighted, as are current clinical practices that allow for manipulation of the LN microenvironment to induce tolerance. Increased understanding of LN architecture, how different LN SCs integrate immunological cues and shape immune responses, and approaches to induce T cell tolerance will help further combat autoimmune diseases and graft rejection.

Radioactively contaminated areas: Bioindicator species and biomarkers of effect in an early warning scheme for a preliminary risk assessment

Concerns about the impacts on public health and on the natural environment have been raised regarding the full range of operational activities related to uranium mining and the rest of the nuclear fuel cycle (including nuclear accidents), nuclear tests and depleted uranium from military ammunitions. However, the environmental impacts of such activities, as well as their ecotoxicological/toxicological profile, are still poorly studied. Herein, it is discussed if organisms can be used as bioindicators of human health effects, posed by lifetime exposure to radioactively contaminated areas. To do so, information was gathered from several studies performed on vertebrates, invertebrate species and humans, living in these contaminated areas. The retrieved information was compared, to determine which are the most used bioindicators and biomarkers and also the similarities between human and non-human biota responses. The data evaluated are used to support the proposal for an early warning scheme, based on bioindicator species and on the most sensitive and commonly shared biomarkers, to perform a screening evaluation of radioactively contaminated sites. This scheme could be used to support decision-making for a deeper evaluation of risks to human health, making it possible to screen a large number of areas, without disturbing and alarming local populations.